Apparatus for feeding pulverized fuel.



V. Z. CARACRISTI.

APPARATUS FOR FEEDING PULVERIZED FUEL.

APPLICATION F|LEDJULY23.1914. RENEwEn JUNE 12, 191s.

Patented July 25, 1916.

VIRGINIUS Z'. CARACRISTI, OF BRONXVILLE, N EW YORK.

APPARATUS FOR FEEDING- PULVERIZED FUEL.

Speccationof Letters Patent.

Patented muy 25, wie.

Application led July 23, 1914, Serial No. 852,771. Renewed June 12, 1916. Serial No. 103,343.-

To all whom t m a .1/ concern Be it known that I. Vnuaxius Z. CARA- cnisrr, a citizen of the United States, and a resident of Bronxville. in the county of estchester and State of New York, have invented certain new and useful improvements in Apparatus for Feeding Pulverizmed, F nel, of which the following is a specification.

This invention relates to apparatus for` feeding pulverized fuel. as for instance, coal dust or connninuted coal. and has for its object to provide an improved apparatus by the use of which the fuel falling on a stream of air is carried by the same. and while being thus supported, is completely enveloped by the stream of air. and simultaneously carried forward b v the same. whereby a thorough mixing of a maximum amount of pulverized fuel with the least possible amount of air is accomplished.

In carrying out the invention, and in the actual use of the same, a return screw for unfed fuel is not needed, as the stream of air is intended to prevent the dropping of the fuel through the stream, a return screw, however, being provided in the event that the flow of the stream of air should be interrupted.

A further object of the invention is to provide a very compact apparatus whichis obtained by arranging the main feed-screw andauxiliary return feed-screw in a direction parallel with the air feeding means and in line with the fuel and air mixture outlet.

One of the features of my invention is to provide a stream of air wider than 'the stream of falling fuel, and which fuel is forced in the same direction as the direction of the air stream, utilizing thereby the energy transmitted to the fuel feed, and at the same time providing a maximum amount of skin surface without unduly increasing the volume of the air supply, the stream of air acting substantially lil/ie a rigid column, but having an upper gathering surface embracingly supporting the fuel.

The invention is shown in the accompanying drawings, in which several embodiments are shown, and it will be more fully described hereinafter and finally lpointed out in the claims.

In the accompanying drawings, Figure 1 is a vertical longitudinal section of my im proved apparatus showing the superposed and parallel feed-screws, air feeding means,

and fuel and air mixture outlet, all arranged longitlulinally of the machine, Fig. 2 is a vertical transverse section taken on line 2-2 of Fig. l, showing a U `vror cup-shaped air outlet orifice, Fig. 3 is aiertical transverse section of a modified form of air orifice, with the upper surface substantially plane, Fig. 4 is another modified form, having the upper surface parallel with the lower surface, Fig. 5 is still another modified form-,showing a plurality of superposed crescentshaped air orifices, Fig. 6 is another modified form of air orifices, showing a plurality of uprightteeth forming a plurality of pockets laterally arranged, Fig. 7 isa section taken on line G-of Fig. 1, intended to show the relative position of the fuel and air-stream at thewtime when the fuel drops on the stream of air,Fig. 8 is a section faken online 8 8 of Fig. 1, showing the stream of air warped or molded to completely surround the `fuel as it is about to emanate from the outlet chamber.

Similar reference characters indicate corresponding parts throughout the various figures of the drawings.

Referring Vto the drawings, and more particularly to Fig. 1, my improved apparatus comprises a feed-hopper 10, below which is arranged a main feed-screw 11. one Aend of which is rotatable in bearings 12 and is secured to an operating gear-wheel 13, while` the other endis rotatable in bearings .14. At this end an opening 15 in the feed-screw casing 16` is arranged at a pointA below the feed-screw, which opening permits the fuel fed by the mainl feed-screw 11 to pass therethrough. lihis opening is arranged in the form of a longitudinal elongated slot, as is clearly shown in Fig. 2, the object of which is to shape the fuel passing therethroughyso that it may take substantially the shape of a cross section of the slot when falling. At

the same time, the momentum imparted to the fuel by the forward-feeding action of the main feed-screw 11 gives the fuel so fed through the elongated slot 15 a forward movement in the direction of the'arrow '18. Below themain feed-screw 11 `is arranged an air supply-nozzle 20. which has its orifice 21, in the embodiments shown in Figs. 1 and .2, in the shape of a U or cup, with the open end upwardly arranged.

The force of the air emanating from the nozzle 20 out ofthe orifice Q1, is such as to maintain the stream in the shape of the carried a vay thereby.

orifice, and therefore provide an elongated U or cup-shaped substantially rigid stream, which extends from the orifice 21 through the chamber 23, its direction being indicated by the arrows 1S, 18", 1S and 18e. Tangenltial to the lower Vsurface of the cupshaped stream thus formed, a plate 24e is arranged, which 'has an inclination to the horizontal, so that. the stream will continually impinge against this inclined plate Q-t and remove therefrom any fuel that may otherwise gather on the plate 24. At the same time. the object of this inclination is to have the plate act to gather in the expanded stream of air. By the inclination, the surrounding casing 23 `is of larger cross-section than that. of the expanded stream at that point. This plate 24: has a circular cross section which is tangential to the periphery of the cup-shaped stream, and forms with the outlet 25, a converging outlet chamber QG, which serves to add to the velocity and at the same time guides :the stream in such a manner that the upper ends of the U are caused to be united, whereby an elongated hollow stream is produced. which completely envelops the mass of fuel carried in the center thereof. and moving in the direction of the arrow 189.

Below the air orifice Q1, an auxiliary screw 28 is provided, which has one end rotatable in bearings 29 and the other end in bearings 30,and is secured at that end with the gear-wheel 3l, which meshes with the gear-wheel 13. Also secured-to the shaft of the screw 28 is a gear-wheel 32, which meshes with a pinion 33 operated by a suitable motor 34, arranged below the auxi iliarv screw QS, as also below the casing 16,

the hopper 10, the main screw 11 and the air nozzle 20. It will be noted that the gear 31 is smaller than the gear 13, by reason of which the speed of the main screw 11 is less-than the speed of the auxiliary screw 28. This is advantageous because it is desirable to feed any'fuel that may have been dropped on to the auxiliary screw 28 quickly a 'ay from the chamber rl`he auxiliary screw 28 is intended to be usedto quickly remove the fuel which is dropped on to it, in the event that the flow of the air stream is interrupted, as when the air stream is in proper operation all the fuel is intended to drop on to the stream and be immediately But by removing any fuel that may have dropped, the air stream, when it again is active, is not in any way infiuenced in its shape, or has the shape which it receives at the time it emanates from the orifice Q1 distorted by conflict with any fuel which may have gathered at the lower part of the chamber or on the deflecting plate Q-f. llt will be noted that the inclination of this plate serves also to cause the fuel to slide off and downwardly on to the auxiliary screw 2S. Any fuel that should drop on the screw 2S is fed by the same into the upwardly-curved chamber 3G, formed by the 'asing 3G", to be taken up by the main feed-screw 11 to be again fed VYforwardly toward and through the elongated fuel discharge opening 15. To prevent any pressure in the hopper 10 exerted by the fuel fed upwardly by the auxiliary screw 2S. a defiecting plate 3T is arranged in. the hopper 10. which serves to guide the fuel in the direction ofthe feed of the feedscrew 1l. and at the same time, due to the space formed beneath it, prevents any fuel from causing a choking action on the fuel fed upwardly hy the auxiliary screw Q8. It is noted. however, that the screw 28 is not absolutely essential during the efficient operation of the apparatus, for the reason that the air stream. vby virtue of the shape that has been given to it. carries all Ithe fuel fed through the elongated orifice or fuel discharge opening 15 forwardly into the outlet chamber. and thereby prevents any fuel from falling on to the auxiliary screw. But in the event of the failure of the air nozzle, it is important to have the screw 28, so that the apparatus may continue to operate without injury to it, or without causing any choking action thereof until the air supply is again restablished,

. and the normal operation of the apparatus again carried out.

The, air nozzle 20 is provided with an air supply conduit Q0, which extends longitudinally of the apparatus, and then is bent as shown by 20", toward the center part of it.

lt will be. noted thatin my improved apparatus. the main feed-screw 11, the air orifice 21. and the air stream emanating therefrom. the chamber Q3, the return auxiliaryy screw 28. as also the axis of the motor if it is so desired, all are arranged in the same direction longitudinally of the apparatus. This provides a very compact structure, and at the same time provides the advantage that the air fiow and fuel flow are in the same direction and not transversely t0 each other, whereby the efficiency of the apparatus is increased by reason of utilizing all the forces acting on the fuel, and not having any loss brought about by a change of direction of forces.

The especial advantage of the cup-shaped stream is that it provides a large skin action of the air on the fuel supported thereby rand the fuel is supported by this stream of air with the large contacting surface and is carried forwardly thereby. Gradually and finally, the fuel is completely enveloped by the stream of air, and due to the increased velocity, it arrives at the discharge opening completely surrounded by the envelop of air. This permits the economical handling of the pulverized fuel by the air, brought about by the fact that all of the valuable energy in the air is utilized, the velocity of the air of necessity being so great so as to carry the fuel as described.

In the embodiment shown in Fig. 3, a stream of air having a vertical transverse section of semi-circular shape is provided by the configuration of the orifice shown in Fig. 3. This orifice has an upper straight surface l1 and a lower surface Ll2 semi-circularly curved.

1n Fig. 4, the orifice 45 is shaped to form a stream of air having the top and bottom thereof parallel, whereby the upper surface may catch the falling fuel. The upper surface of the orifice 15 is straight as indicated l by L7 and the lower surface 46 is also Vried by the lower pocket.

straight.

In Fig. 5 is shown an orifice .with a plurality of superposed pocket like orifices, formed by means of crescent-shaped air streams. It will be noted that the upper orifice 50, in the embodiment shown in Fig. 5, is somewhat thinner than the lower orifice 51, and the advantage of this is that the upper pocket will serve to support and carry fuel, but will gradually permit the" fuel to pass therethrough, and drop on to the second pocket, and then be supported and car- By this initial permeation, the efficiency of the ultimate mixture of fuel and air is materially effected. It will also be noted that by these superposed pockets, which are in the embodiment shown in Fig. 5 vertically arranged, large skin contacting surfaces are provided, so that the largest amount of fuel may be distributed over the large area of the air stream.

In Fig. 6 is shown an embodiment with laterally-arranged pockets, whereby a large skin action and surface is arranged. The orifice has teeth 61, 62, 63 and 64 at the upper surface thereof, and a circular configuration at the lower surface thereof. (lf course, the shape of the-teeth may be changed as desired, and also superposed air streams of similar configuration may be provided.

In Fig. 7 is shown the intended coperation of the stream of air, indicated by 731 and the fuel indicated by 70, just at the moment when the fuel falls on to the stream of air. By the flow of the stream of air into the converging chamber 26, the end portions of the air stream are caused to envelop the fuel as the envelop 82 of air, completely surrounding the fuel 81, in Fig. 8, shows. The m fuel depressessomewhatthe air, as is indicated in Fig. 7, and similarly, when usingv the orilices shown in the embodiments ofy Figs. 3 and 4, the upper plane surfaces are somewhat depressed by the weightof the fuel, so that by reason thereof the stream of air really serves to embracingly support the fuel, somewhat analogous to the curved or cup-shaped embodiments of Figs. 1, 5 and 6.

These various embodiments shown in Figs. 1 to 6, become especially important, when it is remembered that experience has demonstrated that a solid cylindrical column of air, having no upper gathering surface, will not cliciently handle as much fuelper unit of air as when greater skin surface is provided, as in the case of the prior art solid cylindrical columns, which have a convex upper surface, the fuel would be deflected and drop off, instead of being carried by a stream having an upper gathering surface, and hence at the mixing point insufficient mixtures would be obtained.

Thus, from the above it appears that the means for feeding the air, one embodiment of which is indicated by 20, the means for shaping the air, one embodiment of which is indicated by 21, the means for delivering the fuel, one embodiment of which is indicated by 15, the means for enveloping the air, one embodiment of which is indicated by 26, and the means for accelerating the air, one embodiment of which is shown by the inclination given the part 26, all cooperate in the manner described.

I have used the word periphery, by which I mean the external surface of the airstream, or outside edge of the air.

I have shown several embodiments of my invention, but it is clear that changes may be made therein without departing from the spirit of the invention as defined in the appended claims.

I claim:

1. An apparatusl for feeding pulverized fuel, comprising means for feeding a stream of air in a shape and state to form an upper supporting gathering surface, means for guiding said stream of air,` and means for delivering on the upper supporting gatherA ing surface of the stream of air in the guiding means quantities of fuel to be carried by the air stream.

2. An apparatus for feeding pulverized fuel, comprising means for feeding a stream of air in a shape and state to form an open upper supporting gathering surface, means for guiding said stream of air, means for delivering on the top of the .open upper supporting gathering surface of the air in the guiding means quantities of fuel to be carried by the air stream, and means for shaping the air stream to envelop the fuel delivered on its upper supporting surface.

3. An apparatus for feeding pulverized fuel, comprising means for feeding a stream of air, means for shaping the stream of air to form an upper supporting gathering surface, means for guiding the air stream, means for delivering in the guiding means on the upper supporting gathering surface of the air stream quantities of fuel to be carried b y the air stream, means for shaping the air stream to envelop thefuel delivered on its open upper supporting surface for completelyv enveloping the same, and means for simultaneously accelerating it.

l. An apparatus for feeding pulverized fuel, comprising means for feeding a stream of air, means for shaping said stream of air to form an open upper supporting gathering surface, means for guiding the air stream, means for delivering in the guiding means on the top of the open upper supporting gathering surface of the air quantities of fuel to be carried by the air stream, means for shaping the air stream to envelop the fuel delivered on its upper supporting surface for completely enveloping the same, and inclined plates in the path of the air current, impinged by the peripherv of the air stream for increasing the speed of move-y ment of the air stream and fuel enveloped thereby.

5. An apparatus for feeding pulverized fuel, comprising means for` feeding a stream of air in a shape and state to form an upper supporting gathering surface, means for guiding said stream of air, means for delivering on the top of the upper supporting gathering surface of the air in the guiding means, quantities of fuel to be carried by the air stream, and means for simultaneously imparting to the fuel While being delivered to the air stream a movement in the same direction as the stream of air.

6. An apparatus for feeding pulver-ized fuel, comprising means for feeding a stream of air in a shape and state to form an open upper supporting gathering surface, means for guiding said stream of air, means for delivering on the top of the open upper supporting gathering surface of the air in the guiding means quantities of fuel to be carried by the air stream, and a delivery opening of a shape narrower than the Width of the air stream for shaping the stream of fuel andfor giving to the stream of fuel a width narrower than the width of the air stream when the fuel is gathered on the air stream.

7. An apparatus for feeding pulver-ized fuel, comprising means for feeding an air or gaseous stream, means for imparting to the fuel an initial travel, means for guiding said stream of air, and means for imparting to the air or gaseous stream a shape and state to receive and support and convey the fuel while being delivered in the guiding means, the travel of the fuel stream and au' stream being in the same general direction as the delivery of the combined fuel and air.

8. An apparatus for feeding pulverized fuel, comprising means for producing a stream of air, means for guiding a stream of air, means for feeding fuel in the same direction as the stream of air in the guiding means, means for delivering the fuel in the same direction as its feed, and positive moving means for imparting to it an initial movement in the direction of the stream of air.

9. An apparatus for feeding pulverized fuel, comprising means for producing a stream of air, means for guiding a stream of air, means for feeding fuel to the air stream in the same direction as the stream of air in the guiding means, means for delivering the fuel in t-he same direction as its feed, moving means for imparting to it an initial movement in the direction of the stream of air,

and means for reforming the stream of air into a cylindrical envelop completely sur-- rounding the fuel and accelerating the movement of the stream of air While thus enveloping the fuel.

In testimony, that I claim the foregoing as my invention, I have signed my name in presence of two subscribingwitnesses.

VIRGINIUS Z. CARACRISTI.

Witnesses:

F. Hose, JOSEPH BISBANE. 

